The present invention relates to an air conditioner for passenger transportation vehicles, in particular, for buses, comprising a refrigerant circuit including at least one condenser unit, through which the refrigerant flows in several heat exchanger coils connected parallel to one another, and a collecting flask receiving refrigerant condensed in the condenser unit and serving to compensate the fluctuations in the refrigerant volume occurring during operation of the air conditioner.
The condenser of an air conditioner is also referred to as liquefier.
Such air conditioners are known from the prior art.
In particular, air conditioners are known wherein the heat exchanger coils of the condenser unit, which are connected parallel to one another, open into a collecting pipe, and the collecting flask is connected to the collecting pipe by means of a connection line which is connected to the collecting pipe via a screw connection.
With these known air conditioners it is disadvantageous that the arrangement of the collecting flask on the condenser unit involves material and work expenditure, and the collecting flask arranged at a distance from the end face of the condenser unit requires a comparatively large amount of space.
The object underlying the present invention is, therefore, to create an air conditioner of the kind mentioned at the outset, in which the collecting flask is accommodated in a space-saving manner and can be mounted with low material and work expenditure.
This object is accomplished in an air conditioner having the features of the preamble of claim 1, in accordance with the invention, in that the heat exchanger coils of the condenser unit open directly into the collecting flask via a respective connection line.
Accordingly, in accordance with the inventive concept the collecting pipe into which the heat exchanger coils of the condenser unit open in the known air conditioners is fully dispensed with. Instead, the heat exchanger coils open directly into the collecting flask via their respective connection lines. The collecting flask can, therefore, be arranged directly in front of the end face of the condenser unit and thus be combined with the condenser unit to form a compact unit.
Owing to the elimination of the collecting pipe, material and work time are saved. Furthermore, the number of individual parts of the air conditioner to be kept in storage is reduced.
In a preferred embodiment of the invention, provision is made for the connection lines to be soldered to the collecting flask. This results in a lower leakage rate than with a screw connection.
For the same reason, it is also advantageous for the connection lines to be soldered to the respectively associated heat exchanger coil.
Alternatively, the connection lines can be formed integrally with the respectively associated heat exchanger coil.
To enable the connection lines to be soldered to the heat exchanger coils and the collecting flask, provision is preferably made for the connection lines to be in the form of copper pipes.
In principle, the collecting flask can comprise a single storage container, for example, a storage pipe.
In preferred embodiments of the invention, the collecting flask comprises a plurality of storage containers which are preferably in fluid communication with one another.
To achieve a separation of liquid and gaseous refrigerant in the collecting flask, it is advantageous for the collecting flask to comprise an upper storage container into which the connection lines coming from the heat exchanger coils open, and a lower storage container which includes at least one outlet for liquid refrigerant. Owing to the force of gravity, the liquid refrigerant collects in the lower storage container and can flow off from it, for example, to an expansion valve.
In order for only liquid refrigerant to leave the collecting flask, the outlet for liquid refrigerant is preferably arranged in a lower edge region of the collecting flask.
Furthermore, to ensure that only liquid refrigerant leaves the collecting flask, it is expedient for the lower storage container to be of such dimensions that it is always essentially completely filled with liquid refrigerant during operation of the air conditioner.
In order to be able to compensate the fluctuations in the refrigerant volume in the collecting flask occurring during operation of the air conditioner, in particular, fluctuations on account of density of the refrigerant varying in dependence upon the refrigerant temperature and on account of displacement of the refrigerant to other refrigerant circuit components (e.g. the evaporator), the upper storage container is advantageously of such dimensions that it is always filled partially with liquid refrigerant and partially with gaseous refrigerant during operation of the air conditioner.
The connection lines conducting the condensed refrigerant from the heat exchanger coils of the condenser unit into the collecting flask preferably open into the upper edge region of the collecting flask, which during operation of the air conditioner contains the gaseous phase of the refrigerant.
In order to be able to compensate the fluctuations of the refrigerant volume occurring during operation of the air conditioner, the collecting flask must have a sufficiently large inside volume.
In particular, it has proven expedient for the inside volume of the collecting flask to be at least approximately 10%, preferably at least approximately 15% of the volume of the liquid refrigerant filled into the refrigerant circuit at 25xc2x0 C. at the boiling point of the refrigerant.
Furthermore, the inside volume of the collecting flask is preferably of such dimensions that during operation of the air conditioner a refrigerant outlet of the collecting flask always remains covered by liquid refrigerant.
For safety reasons, it is advantageous for the collecting flask to be provided with at least one connection for a pressure relief valve, by means of which gaseous refrigerant can escape from the collecting flask when a threshold pressure is exceeded.
It is particularly expedient for the connection for the pressure relief valve to be provided on the upper storage container, which during operation of the air conditioner is filled partially with liquid refrigerant and partially with gaseous refrigerant.
To increase the cooling capacity of the air conditioner it is advantageous for the collecting flask to be connected to an undercooling section of a condenser unit via at least one connection line. In this way, the liquid refrigerant collected in the collecting flask can be cooled down in the undercooling section to a temperature below the boiling temperature of the refrigerant.
In particular, provision may be made for the collecting flask to be connected via several connection lines to a respective undercooling heat exchanger coil of a condenser unit. The refrigerant throughput through the undercooling section of the condenser unit can thereby be increased in a simple way.
A condenser assembly comprising the collecting flask and the at least one condenser unit can be arranged on the roof of the passenger transportation vehicle, in the direction of travel in front of or behind an evaporator of the air conditioner or between two evaporator units of the air conditioner.
If the condenser assembly comprises two condenser units aligned parallel to each other, the collecting flask is preferably arranged symmetrically in relation to the common longitudinal center plane of the condenser units in front of the end faces of the latter.
The condenser assembly with the collecting flask can also be arranged in the trunk of the passenger transportation vehicle.